Extremely high CHT during engine runup
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I was doing my runup and noticed my CHTs were both very high, above the red line. Outside temperature is 19C. Note that I was speeding through the run up so it wasn't like I was sitting there a while...maybe 3 minutes. Cowl flaps were closed at that point. I immediately opened them but it didn't seem to have any effect (or not much).
Help is appreciated.
Gregg -
I'm actually on the phone with the Duke owner who contributed the most to this project right now, so you're getting the most accurate information possible!
He says that cowl flaps closed during runup would be a sizable mistake, and he would expect redline CHT's within a couple of minutes. At normal ambient temperatures, the cowl flaps should always be fully open for run-up, and even then, a prolonged runup may have to be split into two segments to avoid overheating, such as between other system checks, and the pressurization and deicing boots checks.
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While on the phone, he actually looked at his own checklists and said, "Well, it's not in the runup checklist, but it should already be open from the preflight checks. Really, anyone flying a high performance airplane should just know that the cowl flaps should always be open for runup."
I would never speak so frankly to my users, but I'm allowed to quote the real world owner :)
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Piston engine airplanes do not like running on the ground. They will get hot.
I leave the cowl flaps open from before start to leveling off in cruise. Then, I don't open them again until after landing. For whatever that's worth..
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@Black-Square There's the difference between someone who's had training and someone who hasn't. He got trained on high performance airplanes so he knows. I'm reading checklists, going through manuals and...youtube. LOL. Sigh. I guess I open them for the walk around.
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@Black-Square Should I assume to open both the oil doors and the Ice Deflect prior to starting the Turbine Duke?
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Neither are required, and the function of both are quite different than cowl flaps. It's advisable to have the oil doors open anytime ambient temperatures are above freezing while starting. The ice deflectors are more of a balancing act. Having them open while starting can promote cooler engine starts, but doing so over dirty ground surfaces can cause the engine to inject particulate matter.
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@Black-Square I thought ice doors should be open to prevent ice and rocks and the like from being injested into the engine. Maybe I have them backwards...closed means deflect the air to prevent FOD and open means let it go straight in?
EDIT: Found this on a RW site:
"Woe to the pilot who forgets to turn on the ice protection when entering icing conditions, lands the airplane on a contaminated surface without the ice door ON, or who uses excessive reverse/beta frequently. A single hunk of ice slung from the prop can FOD an engine completely."
So the question is...is ON open or closed?
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@seipp On is open. You can see it on the tablet. Just go to the tablet, select an engine and then open the ice door of that engine. Then look at the bottom right corner of the tablet.
In fact, Im flying right now and there's some ice. I just noticed that on the air intake, ice is depicted as floating blue dots. Before I opened the doors, the little ice chunks where going to the combustion chamber. Now with the doors open, i can see de ice entering the engine but exiting it at the ice doors.
Very neat animation there @Black-Square !!
